Magnetic particle inspection (MPI) is a non-destructive testing method used to detect the presence of surface and sub-surface discontinuities. A magnetic field is formed or applied into the material and ferrous iron particles are applied. An indication is formed when the iron particles gather in an area of magnetic flux leakage. This indication can then be assessed by the operator under either ultraviolet or white light.

Penetrant Testing (PT) also called Dye Penetrant Inspection (DPI) or Liquid Penetrant Inspection (LPI) is a non-destructive testing method used to locate surface breaking defects. A dye is applied to the material and allowed to penetrate. The dye is then removed and a developer is then applied. The developer draws out any dye which has been held by the surface defect. This is then made visible to the operator either under ultraviolet or white light.